SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ef9f954f4482b2a722201e36e33be7188f5e3fdea3eb1759005d8cfa76d1909' 
  AND token = 'Rn8KAJArFGCyMmCe7cJRt3GlwTqqFR6eV0vibnqCAS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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