SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74d67aa0ae0082fbef3a0a07523b4ec57982017d8c5d02e43d4c13a097a28cfc' 
  AND token = '9GFuS7nYD0tkle+DOwDNUTcTJIN1bc0mMhujPKD1mIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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