SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e401419f2f3e0c970f3dce77011f10256f8d65664e362636eeaa1ec2b55bb865' 
  AND token = 'kEscrSWYhcdR8o3sGn2my985V9Cj78AqXtnE9mCE+YY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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