SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1efcbdf6d88c42411bfb03173e356424a00c20bd22da122a99d23b18349f999e' 
  AND token = 'xm2L7HX1IqpKj3AZ1qMaplqcy8hms52gXEJWbzY7CGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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