SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548d398de6664fd01c4c5a444b35c877bd1958679b196dbe04a41ee5542592c4' 
  AND token = 'V6wrhkVgHF1XAEKv9HKRRm4o0gZxvGPnV6QZY5TDkVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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