SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f1f433ee970a47c65566e3104121ca4ca48bd9a1791753198ef68516b02f749' 
  AND token = 'DobZSfgAJeXW2okAu4BdXInJMo8GE4MX+Q0BqYqoUJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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