SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bae91becfe097458b2dfbc2e2537534b38eec96e55c087bd63e210d79a19538' 
  AND token = 'A5frw5qDZ/heEOznoycHYYe9VxQv3nUUZ6oYY1YSAcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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