SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd000b6858668d87393afd664752d3b0d156c295dda433044965539534fb8e6a8' 
  AND token = 'crZ/U1HZfwV+k3XnpQbRTgw43FykpYq5mqtbojCKMEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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