SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff3057e79d63581602325bc48214b0186ed05495b2cb0d670d3132d79434f996' 
  AND token = 'ZcHhjq9FVI5OmsNrE9X577KwgtBL9tJO+gkwkr/tnms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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