SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f481ab478c919bd603194b1e7aa6f0f8e4173d422f165cb683681140c29b1569' 
  AND token = 'GRbneiIP4QdimmmQuG2NB7wjPZEL0IiG/1U8rdmvUAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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