SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50603433afb4eb351efbc7b8f9ebdb4ba83615e851ac4cf1c75c7bcfaed63ffd' 
  AND token = 'fKx2jqUb8Bfw9d1shrzlMx5CVGYUKd/K0GSxOeadBE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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