SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b091885e3bab3e9836ccaf6323ab699eefd6e046c6e84f19013a8bd4c4b085c' 
  AND token = 'BJ2gHqEMz8RO/dZJY5vDXLnp+DsVrmPUe3SYDLsHETw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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