SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88449c9234cf5ef7dad5a07ec2f02b744b81007abdaf5b36b1fcc9ee3ffa27a6' 
  AND token = 'iznOm+KCVK2L0kBPVHLQCgiHSRNdpmpN/+aQZDwQHks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}