SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a7a99312acb2fdaba2a7b8c7720def093e325dc10619ace15aa894cb19e62bf' 
  AND token = 'x5PjHXLnBgJBkrJ3Tr6r/hJLUkikZYyoa/cnsfOtYOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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