SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92ca4cfd093f08ebcc90f089fbd9fc5710d778a108d64503815b34c52f6e0a00' 
  AND token = '+gFs8AnoJh0mIvMJKQeh7KdzhHxQYv4oZcWKWwrdfxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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