SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '145489db4e24ace9ffba6af026517827dd9bbd4f92b53e936f06396270b8c761' 
  AND token = '9XA6CnaBPpvcyHXKwwNY+r+MrFpDn8FjItP5MjtXjBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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