SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18ce43dfb8a96db0dec44ca49619ae073784afedb961d1aee697cb81d99b1eb2' 
  AND token = 'ZnEbTMZ0zcjuJNBahTP1FfrEVJ+EHwRXBNNzr1K/oUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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