SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b40d5352c756675fb6f3eb323ed40ecba3512e3bbd126b6b90341d749da5f278' 
  AND token = 'GE1bMvTTfNfeId8gRqWf9QG1w5X4K0xYwoetOlWagWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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