SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1621ba84cece9bc23784933f822db50281f6fee80b0e987cc199380ec86d73c6' 
  AND token = 'kG84nU8M4AUlAe22CXtTlxu4Bm1IKgpg6SykKMgZBwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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