SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42aa8225a0a25efa08f2bb12971eaec4fe1632b31d3dd6a5e8ae76fbf99e7d7a' 
  AND token = 'lZ5nB4jrurLEo9M3eDH/H/kSKIYtYH+5n5wqqeo9bXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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