SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb8d1670ba0c2b73ca161e88eb7a7cfe3bf07fb263eb8402363aaee19ae2614e' 
  AND token = 'MGmK6/zm7+SOKmH6tEz9sI2/m0eEQhvg26bmW/oYNho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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