SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6721880c6998a966b07e554ebae64385cecab30d9756119120bc6bcbcaf61aa7' 
  AND token = 'HlCX1PpQweEg5THcMdIHKQ1WBJm31LTwVhQs3HEYX5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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