SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8b9277efcd2575a86b4dd9a619adcd084b449ff5d419e8097ad4241d6fdca30' 
  AND token = '4rDUltDDGmY+idzvSy35wGJiug0dN74hUtuk14NL+y8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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