SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '99100127c7518fecc420012abece156161893a41c78761540af6498038a14e17' 
  AND token = 'cg2hCkWHO2wguDSXwzUNRPJoBaP3Cxz4qrvZy0IQZxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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