SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0591e3efaa9f7c4eefeb429a462c4d039ad9c773adf7414a67bcdc11a610d058' 
  AND token = 'dx8ovUAiveMxMJejnB608w+QSKb6z9lDkinzlrZmvR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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