SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f8319c91a91a6a55ba3bcd02b098299ef0dc5a357137074271d87fd1917679' 
  AND token = 'ZXu3bjmtn4ClRSU3qtyivtxQZFLqceANZsP0mN+iJCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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