SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6030c931b2da450fd02aef5ae75fa34ea6de849713c3040fc0f1007e2aee814a' 
  AND token = 'yM/m2SKb985vo4f3Yw3o1BWXL0NLRfRqU+NvAm6kqVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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