SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e527515b86e0cec60ee8f7d8ef05c81c6a63b99719a399f0872608be9b38e251' 
  AND token = 'GmKVTINGsOyllTjsZS4U3nxLAH7e3Kc6kziaoy+3k8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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