SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ff4bfc9098d5a41c7640047a47095a129cc57c348764542d9c694e4e8b0fb6e' 
  AND token = 'ptdLFYtZKprJDPiUGhg93aBgxWf9b3pdah+oQQSBvzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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