SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9553d121ef908d30cbaa540fab9482729f17c5847631fd2dce67954a3cc77474' 
  AND token = 'iMEq7/GU+3QUxAmzWYIpBjs5SJYUSUZDb3/wxkMA8EU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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