SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48a39f1b3eedc47cf14f168f6d7b7d9b5adbbef699c4bbcfb22704177c6e2d28' 
  AND token = 'OQWgRmK4m1WGHPECNzYl9sA9SEKLRVzWaHueDVbexIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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