SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8792cd9cabe22bb2759f028096bfbb73253587867e078e66a7363d466c8f2a3a' 
  AND token = 'cimPYADzdsVI3gqs7W20XegYrPMUzV295FEAJ6aFdGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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