SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7af2dca9b6d7883b3cd4a31a556022dde8deba98fe25321d6edc58a80c3eb90' 
  AND token = 'mqUJXmmAfuvjS+PZqXWHwL8r1Y1FhpxLh4tVlrdQDHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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