SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68786a422c47320493359a847c62c5a3100cf64fecfb55048aaa44159f3b7ce7' 
  AND token = 'L6P+4WmFtHgTKwyWGhPqxKiK6tiP0BBuEOhG3RQQAXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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