SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '357f537557067cd832d308634cd453397909827f0daeabe62b545a329db44e9c' 
  AND token = 'eaxz92haKZ52fA3IfyBNKfxXpNhPCr9uhaUWHFbHaDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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