SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6881cf5ba65048af7a5b3fbba9e36e50b1abaa53872759fd91e2c82cbf974c42' 
  AND token = 'mmjDv0v+Jq1GYsLjbkl/m/umUoJfRA67pRhob/A3gew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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