SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdde1b726413bb37f456c5efb4009a5c256e77a6109d3ed91f73815ebd28c10c' 
  AND token = 'KLcVtftgYKG7sTVYu7Ebs+vZ3zvcKYa8oHsLTpwJhwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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