SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '651db76f025897f4b7fc4fd631e2dab5f428de1a9878c45ea64f1b55ebf779eb' 
  AND token = '/0tA9EKjabUbiQJsIbpMJlPor7rsoj7yJfGZRrmffxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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