SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '305346ae833510de6fd44e7b51644cd9bcebd5948d66cb6abd7a9851c1b3149a' 
  AND token = 'lC6CfxafdWYaCFJpdyACDDMh1hdLeo0kZpGiG229mPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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