SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df257d080fe99e2121da3107f4576b982dda1c80a064e7a3dcca92cd48bc57fe' 
  AND token = 'z9kyoXvZlPpysw6wiQMNfjZFp7WPOGAUjLMxX1kbaRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00071

JSON explain

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