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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e35081b6d37781c277c09336e93e3d0c6a9c611e66ba8c2eb57d0e208ea3521' 
  AND token = '0Sm/COY4TCfLU9Jo8nrquOPlk0KP89ssrxUlbvsPRgw=' 
  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"
    }
  }
}