SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5000f0620e8479b09981931fc8345fa1e8606688f20cbc80aded49ce68af5f8' 
  AND token = 'X+SpKYGAUxxKYsSMol4yqKbUtNWUyP5tAsNGF7z/n9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}