SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b436a85d7fc67659191ec667e1735641141ed37ada5a481a68ab747703254c2' 
  AND token = 'JpX0Zz+dyHWrWxKnmp0/BBmUJTYB2GQgMMjfNXQ//sk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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