SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd3210493ee876f144a52baaeca6b019d1cf812b20749b728ff873e756156d63' 
  AND token = 'U8UOwMQ2mFVf3mBr51J4nPXxbEFS3HwjSKIzowYPNMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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