SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c91c1e2c846157ae540b65870611d241e6a4fa61b26531efb3178a2cc6e4608e' 
  AND token = 'zgV2kozHJVpjClTn4+WMaQ2o+wa0PUyIIaHypMVQgc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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