SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a599cc1543d19a7e1a454b8cbce429e19f76d63d6928a473c305b5bab303e061' 
  AND token = 'OMx7lPU/BfuRsWKkFsg81MrV+CdU2oywgq4wjUB5AJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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