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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57b5ce4b72394a4deb669ad89efc70fd4c1d3d6d08eba5ecd7c54cf50ab09383' 
  AND token = 'dP+E7Az/GpCSRABLg8AIsCy7y3FouuoXeV63x/X+bcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}