SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1771712cba6ced3f7fbc5cf3bb1add7c105cc6400357734bda8b082499685ddd' 
  AND token = 'PSnCOBE96nrJxsKz1QALZ/LKBBl6qiaiTWpfR4FQtVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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