SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '706df018001e55718d3ff0b9653b38bc1eea2970aad1ad4759d94cf610338054' 
  AND token = '7bIrpOAfdcLZfEdXcDh58DC3cpoKtf+7rhXapPfAPdM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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