SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d423f2a0489b769d9a265f5dca57f16e712a299bdb36fa61fcc03934925fcbd' 
  AND token = 'T+fEdcutgilEAbTZqkvxelpobbgYGOc1kxgi0aEPNmk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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