SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2f527792ca7281f3de23852b1027c7f540e67d23649782676fa909899b9b3f4a' 
  AND token = 'mcjS6qcgsiAAytVZbhvIZWjzvHXNtCTqnIa2KPy546U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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