SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4bed5d8246842f3313218840e941537292263d29344e1821e2e050374c1033a' 
  AND token = 'WlS5Vju9BMnOLXsq3mk226u4KsxV+Sk/eYhwv2TonR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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