SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21330532ae05698b411703bea2fab22ad1771d587bbf9b0b05b61cd77bc4b927' 
  AND token = 'tW/FwQEVQ6epkIqTBwVy7R3RbIcUq1UdCCELLE63iVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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