SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a936072831790be5857216539df8eecd15fd47eaebcc69f241ba450f31467a3d' 
  AND token = '3NbtYmR3jX0ZZvwGSzQ9y3hSOmWTUbzi/v4BvsBJUeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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