SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '702074cfc0fde78574a766aa0d869c956c5e2184d2e1bd94f558c2376f43c7cd' 
  AND token = 'dS/SmAWeCQ+KirWBo/F68ZhbBxAWXIMJUVzJFZU/mSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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