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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7fc21b4a5dc300cb64bb331fd4466cd4bd4fc5d86dc91b4b78c27bcfb2ca8e4' 
  AND token = 't8DdxprOz3RhRJtESERYavqzV7/28P7GPvaOmwu0FJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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