SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e918848a0270f15b172220e372fe2ba4431f5484bf1f9fafee8e94d0f20d9817' 
  AND token = 'rjpKUY5TvhHP0Mi0osXGpo6kHlMN8mymZfU7zM0NwTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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