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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e840b31174eef24019f5c964e9811f8984615f79495e9c19d3a983b2467ab67' 
  AND token = '1eTkzAcqV2UjrMNL0nEPngXylyMPX6XuRWDjaQoS0B4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}