SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfe5c42e40a99b0669928e6a2b3c25f03e21476da5306434039cf2aa5ee87654' 
  AND token = 'eS//ZSbiF9Qm/Rym3qDsvZ7lNIdFZ6oUGUBAxEHeEac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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