SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6e0226748ecaf5a5b73b89aa2454dac2cb58f2c1d82cacbff797b4b94e08a44' 
  AND token = 'AbaPlELkshl1sRfazvzfzkGpOhiChlTFfrQNim+Nj9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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