SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd40efdc477ddcdd353793266e1c8009f48e09be83f6aa3a1fd4082d8708dc1a6' 
  AND token = 'fm7sCXnlnDfa258yWdngjVFwsgA0SFTLW0j8JctXkPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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