SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75968dd6cb55eff1f72269bcb4d753ec61a5c6bd10f01b26178aa73e1bb06e9e' 
  AND token = '+0tRWOOjGxBaxgTZvBKLbyhztw8U5SlXoBX+kCGzbTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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