SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39d2151b4964a172de7bfda08ab3c022079994c7a8a9da87b0a7f5a813c5dce' 
  AND token = 'cL11Vcaz0xtLeY1IXNXOsLpZWP5jys86oHV4GaLEvIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}