SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d8feefbfbb456d7de6bbd093df686dd71063b574cbe885e038e649e176284f1' 
  AND token = '/A+46scPqjikKySf/H7tW26V5oPawKpM+qd3QrgZwOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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