SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a736d71e499135540055446a93f5de4450e6c7fe0b2e71b3a6a098f01b2d426' 
  AND token = 'xZQzw2Lhcci7q82+llbATGQk/mTU7IBK33/9/JCV9/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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