SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9f81886570bf8eea79f688f22b4968305b7210b1e4060e5a136711c155d6bdc8' 
  AND token = 'Upck35ffHp+G7M/RDXw5o4um3Z3Uo9izsqqD1ItLypM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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