SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8729af807659a6da8590d57278456a1a2f87c2c1659fe3e989c57a6b08fe4231' 
  AND token = 'ZLotvVK/mZNV2qQnyeLMI/ClHkBjoDCY/JtVVi2Rd2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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