SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1f21a98e64b9527dbd956f92798a3c691ea3c76739a1a341ad6f0f259484911' 
  AND token = 'RA+8sIAPLtMIKEZ8tfRTkN/hmhj0zmVLtMTvgohlmos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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