SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'daae9c50bdb9c94a636b33fad41cb48321a41653c58d67a71c8b1052f8dc2c46' 
  AND token = 'eiqBYEXcwMEsa/yQ9Iy1o2yPJUnaKgs8wjDbaxgPdcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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