SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81409b54692a8405ad4440d79c0352a3adc6f009b032b9f6774d11858f089ef4' 
  AND token = 'IFVf5hVQi8q67NvvAf2lU2hVqvWVfdg6s42GG2flbSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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