SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a4ab6856633ece6d2410c89101677693e861a4eddd050a08a945e8691aa73f52' 
  AND token = 'TUAVbM63ruNGtPc2u4jycJ1K2/GN4JIKDhpbn0dgYzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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