SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f64078cf16391610df50d586e1a63d6f54fa7c1aa81eaaaa518f701e2b3be731' 
  AND token = 'jX78S59OUga6FK5tYkg1ELqCUrI++W1RrzFTeoGJbAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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